Introduction

Twenty years ago, Knapp et al. (1978) published the results of a systematic search for HI in dSph galaxies using NRAO 91 m & 41 m single dish observations centered on the optical position. They reported that no HI had been detected within their single beam, single pointing observations, setting upper limits in the range of 10²-10⁴ . More recent observations (Mould et al. 1990; Koribalski, Johnston, & Otrupcek 1994) using the Parkes 64 m telescope yielded very similar results. Since then, those papers are often cited as evidence that no ISM is present in dSph galaxies and that, because of their shallow potentiel well, they probably lost all their gas during their first episode(s) of star formation (SF) which took place many Gyrs ago.

However, without knowing it, Knapp et al. (1978) were the first to detect HI in the LG dSph galaxy Sculptor. In fact, in their paper, they mention a peak in their spectrum around 100kms^-1, but discarded the possibility that this gas could be associated with Sculptor because of the wrongly determined optical velocity at the time of kms^-1. The optical velocity is now known to be kms^-1(Queloz et al. 1995), very close to the gas detected by Knapp et al. (1978) at the Sculptor position.

© Copyright Astronomical Society of Australia 1997